Exam DP-420 All Questions

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Exam DP-420 topic 1 question 6 discussion

Actual exam question from Microsoft's DP-420

Question #: 6
Topic #: 1

You are designing an Azure Cosmos DB Core (SQL) API solution to store data from IoT devices. Writes from the devices will be occur every second.
The following is a sample of the data.

You need to select a partition key that meets the following requirements for writes:
✑ Minimizes the partition skew
✑ Avoids capacity limits
✑ Avoids hot partitions
What should you do?

A. Use timestamp as the partition key.
B. Create a new synthetic key that contains deviceId and sensor1Value.
C. Create a new synthetic key that contains deviceId and deviceManufacturer.
D. Create a new synthetic key that contains deviceId and a random number.

Show Suggested Answer

Suggested Answer: D 🗳️

by kdsingh at May 9, 2022, 5:43 p.m.

Comments

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muks1003

Highly Voted 2 years, 6 months ago

Selected Answer: D

D is the correct answer, I have taken the Microsoft Official Test And the answer is D.

upvoted 13 times

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praticewizards

Most Recent 2 days, 7 hours ago

Selected Answer: D

it is correct

upvoted 1 times

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biglebowski88

6 months ago

Selected Answer: D

I believe there is a tradeoff between the huge fragmentation for D and the possibility of hotspots you get with the other options, Since this is a write heavy high volume application then the primary concern is reducing bottlenecks associated with hotspot partitions.

upvoted 2 times

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[Removed]

9 months, 2 weeks ago

Selected Answer: D

Answer is correct

upvoted 2 times

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Gall

2 years, 3 months ago

Selected Answer: D

Because of frequency (1s) we may not want to put too much data into the same container. The maxim quota for logical partition is 20GB, which can exhaust pretty fast.

upvoted 1 times

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ognamala

2 years, 4 months ago

Correct answer is D as per this link https://docs.microsoft.com/en-us/azure/cosmos-db/sql/synthetic-partition-keys - in order to avoid a hot partition we have no option but to use a strategy like that suggested in the section "Use a partition key with a random suffix"

upvoted 2 times

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chukismit

2 years, 5 months ago

D, it's the right answer because deviceid a with pre-calculated suffixes number (Second when data is inserted) It will create 60 partitions by every deviceid

upvoted 3 times

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jfarrell

2 years, 6 months ago

I get the reason it is D BUT, there is context missing that would be necessary. For example, does this mean that the devicid for like devices is the same and somehow hardware bound? Also, the suggestion of a random number is not inclusive of how random the number is, obviously if its generated with each send you will create excessive partitions

upvoted 2 times

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lakime

2 years, 7 months ago

Selected Answer: C

Fully agree, I would either select C, or have an answer - deviceid

upvoted 2 times

lakime

2 years, 7 months ago

Sorry - I'm changing my mind ;) I guess B makes more sense in that case, we got two options (True/False) - and creating synthetic key when probably devideid will have always same manufactor - doesn't make sense

upvoted 1 times

ognamala

2 years, 4 months ago

C and B are both wrong, the both can end up creating a hot partition because of the low cardinality

upvoted 1 times

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kdsingh

2 years, 7 months ago

D, can't be the right answer because deviceid and a random number will create a new partition on every document you will write to the database.

upvoted 3 times

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